III-nitride semiconductor device with trench structure

Abstract

A III-nitride trench device has a vertical conduction region with an interrupted conduction channel when the device is not on, providing an enhancement mode device. The trench structure may be used in a vertical conduction or horizontal conduction device. A gate dielectric provides improved performance for the device by being capable of withstanding higher electric field or manipulating the charge in the conduction channel. A passivation of the III-nitride material decouples the dielectric from the device to permit lower dielectric constant materials to be used in high power applications.

1. A heterojunction field effect device, comprising:
 a first III-nitride semiconductor body having a first band gap; 
 at least one trench formed in the first semiconductor body, the at least one trench having opposing sidewalls and a bottom; 
 a second III-nitride semiconductor body having a second band gap different from the first band gap and disposed on the sidewalls and the bottom of the at least one trench to form a III-nitride heterojunction with said III-nitride semiconductor body that includes a two dimensional electron gas along the III-nitride heterojunction at the bottom of the trench and no two dimensional electron gas along the sidewalls of the trench. 
 
   
   
     2. The device according to  claim 1 , wherein the device is a vertical conduction device. 
   
   
     3. The device according to  claim 1 , wherein the device is a planar device. 
   
   
     4. The device according to  claim 1 , wherein the device is a substantially horizontally conducting device. 
   
   
     5. The device according to  claim 1 , further comprising a conductive gate material deposited in the at least one trench. 
   
   
     6. The device according to  claim 1 , further comprising a contact coupled to the channel. 
   
   
     7. The device according to  claim 6 , wherein the contact is an ohmic contact. 
   
   
     8. The device according to  claim 6 , wherein the contact is a schottky contact. 
   
   
     9. The device according to  claim 5 , further comprising another gate contact, wherein the device includes complementary portions. 
   
   
     10. The device according to  claim 9 , where in the complementary portions are operable to produce isolated conductive regions for confinement. 
   
   
     11. The device according to  claim 1 , wherein the first and second semiconductor bodies include at least one element selected from the group consisting of Ga, Al and In. 
   
   
     12. The device according to  claim 1 , further comprising:
 a multilayer III-nitride stack, including two III-nitride materials adjoining each other and having different in-plane lattice constants to form a conduction channel at their interface; 
 the vertical conduction channel being coupled to the stack to permit current flow through the conduction channel and the stack. 
 
   
   
     13. The device according to  claim 12 , further comprising a contact coupled to the stack and operable to conduct current into and out of the stack. 
   
   
     14. The device according to  claim 5 , further comprising a high dielectric constant gate dielectric between the gate contact and the channel. 
   
   
     15. The device according to  claim 5 , further comprising a high dielectric breakdown gate dielectric between the gate contact and the channel. 
   
   
     16. The device according to  claim 5 , further comprising a piezoelectric gate dielectric between the gate contact and the channel, and operable to alter the charge in the channel and adjust the electrical properties of the device. 
   
   
     17. The device according to  claim 5 , further comprising a pyroelectric gate dielectric between the gate and the channel, and operable to alter the charge in the channel and adjust the electrical properties of the device. 
   
   
     18. The device according to  claim 5 , further comprising a gate dielectric between the gate contact and the channel, and operable to alter the charge in the channel and adjust the electrical properties of the device. 
   
   
     19. The device according to  claim 1 , further comprising a trench structure having sidewalls oriented in a vertical direction or a direction that is at an angle to the vertical direction. 
   
   
     20. The device according to  claim 1 , wherein said at least one trench is bounded by at least two mesas and said second III-nitride semiconductor body extends over said mesas.